With reference to FIGS. 1 and 2, which depict an arrangement of the prior art, a rotary feeder (not shown) picks up a collapsed paperboard carton 8 with vacuum cups 10, at least partially erects the carton 8 using centrifugal force, and places the carton 8 between flights 12 where the carton is fully erected. The flights 12 move the open carton 8 in a downstream direction, indicated by the arrow, where the carton 8 is filled with cans, bottles, or other type of product. A rail or ski 14, which is positioned slightly downstream from the rotary feeder, maintains the carton 8 in an erect position after the vacuum cups 10 release the carton. The carton thereafter moves underneath the ski 14 to a carton loading assembly of the packaging system. The ski 14 must be carefully placed to not interfere with the erection of the carton 8, yet still be close enough to hold down the carton after it has been released from the vacuum cups 10. If the ski 14 is positioned too far away from the carton 8, the carton 8 may partially collapse before reaching the ski 14, and push itself out of the pocket created between successive lugs or flights 12. On the other hand, if the ski 14 is positioned too close to the carton 8, the carton 8 will not be erected due to the carton 8 colliding with the ski 14. It was therefore difficult in the industry to place the ski 14 in its optimal position.
FIGS. 3 and 4 also show such a prior art arrangement. FIG. 3 shows a typical overhead rotary feeder head 20 comprising a stationary central sun gear 22, an idler gear 24, and an outer planetary gear 26. The rotary head 20 rotates in a counterclockwise rotation about a central axis 30, while the vacuum cups 10, which are attached to elements (not shown) driven by the outer planetary gear 26, rotate in a clockwise direction with the outer planetary gear 26. A J-hook 28 also is attached to the outer planetary gear 26 and makes momentary contact with the upper surface of each carton 8 as the vacuum cups 10 release the carton 8. FIG. 4 is a graphical, cycloid profile showing a variation of the distance from the J-hook 28 to the carton 8 over time. As shown in FIG. 4, the J-hook 28 makes only momentary contact with the carton 8 for each rotation of the outer planetary gear 26. Since the J-hook 28 holds the carton 8 down while the vacuum cups 10 release the carton 8, the rail or ski 14 may be placed slightly further downstream. Thus, the placement of the ski 14 is not as critical with the use of the J-hook 28.
The J-hooks 28 are attached above the vacuum cups 10 on a vacuum stem 9, and in the prior art, had to be precisely located on the vacuum stem 9 in order to make only momentary contact with the carton 8. If the J-hooks 28 were located too high on the vacuum stem 9, the J-hooks 28 would not make any contact with the carton, and the carton 8 would be left free to collapse. Conversely, if the J-hooks 28 were located too low on the vacuum stem 9, the J-hooks 28 would extend below the top surface of the carton 8 and would exert force into the upper surface of the carton 8. In addition to being difficult to properly adjust, the J-hooks 28 frequently moved out of position during the operation of the rotary head 20. Once the J-hooks 28 have been moved out of position, the J-hooks often come in contact with surrounding parts of the packaging machine, thereby damaging those parts.
It was therefore difficult in the industry to erect a carton 8 in such machines, and maintain the carton in its erect position as the carton moved in a downstream direction. It also was difficult in the prior art to hold down the carton 8 for various configurations of the vacuum cups 10. Previously, when the rotary feeder was adjusted for a different shaped carton, the vacuum cups would be placed at different positions on the carton, thereby requiring the J-hooks to be repositioned as well. Since the positioning of the J-hooks 28 is difficult, the process of adjusting the rotary feeder to accommodate a different carton is also difficult. Also, because of the time wasted in placing the ski 14 or the J-hooks 28 in their proper position, the rotary feeders became inefficient.